includelinuxkobject.h
struct kobject {
const char *name; //name
struct list_head entry; //链接到kset建立层次结构
struct kobject *parent; //指向父节点，面对对象的层次结构
struct kset *kset; //指向所属的kset
struct kobj_type *ktype; //attribute type
struct sysfs_dirent *sd; //
struct kref kref; //Reference count
unsigned int state_initialized:1;//初始化状态
unsigned int state_in_sysfs:1;
unsigned int state_add_uevent_sent:1;
unsigned int state_remove_uevent_sent:1;
unsigned int uevent_suppress:1;
};
includelinuxkref.h
struct kref {
atomic_t refcount;
};
void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
{
...
kobject_init_internal(kobj);//进行主要成员变量初始化
kobj->ktype = ktype;
return;
...
}
EXPORT_SYMBOL(kobject_init);
static void kobject_init_internal(struct kobject *kobj)
{
...
kref_init(&kobj->kref);//初始化reference count为1
INIT_LIST_HEAD(&kobj->entry);//prev和next都指向自己
kobj->state_in_sysfs = 0;
kobj->state_add_uevent_sent = 0;
kobj->state_remove_uevent_sent = 0;
kobj->state_initialized = 1;
}
int kobject_add(struct kobject *kobj, struct kobject *parent, const char *fmt, ...)
{
...
retval = kobject_add_varg(kobj, parent, fmt, args);//add操作
...
}
EXPORT_SYMBOL(kobject_add);
static int kobject_add_varg(struct kobject *kobj, struct kobject *parent, const char *fmt, va_list vargs)
{
int retval;
retval = kobject_set_name_vargs(kobj, fmt, vargs);//设置Kobject名字
kobj->parent = parent;//设置Kobject的parent
return kobject_add_internal(kobj);//sysfs中添加kobject信息
}
static int kobject_add_internal(struct kobject *kobj)
{
...
if (!kobj->name || !kobj->name[0]) //如果名字为空则退出
{
return -EINVAL;
}
parent = kobject_get(kobj->parent);//如果parent为真则增加kobj->kref计数，也就是父节点的reference count
if (kobj->kset)
{
if (!parent)
parent = kobject_get(&kobj->kset->kobj);//如果kobj->parent父节点为NULL，那么就以kobj->kset->konj作为父节点，并增加reference count
kobj_kset_join(kobj);//把kobj的entry成员添加到kobj->kset->list的尾部，now 层次就是/kobj->kset->list指向kobj->parent->指向kset->kobj
kobj->parent = parent;
}
error = create_dir(kobj);//以kobj创建目录和attribute文件，其中会判断，如果parent为NULL，那么就于sysfs_root下创建
if (error) //创建失败，减少相关的reference count
{
kobj_kset_leave(kobj);
kobject_put(parent);
kobj->parent = NULL;
dump_stack();
}
else
kobj->state_in_sysfs = 1;//创建成功，则object已经于systfs中了
}